I intend to build my house in the country when the frost comes out of the ground in the spring, and around this part of Canada that will be in late April or early May, depending on how much snow cover we get. An operator told me that it's not a bad idea to dig a basement in the fall and leave it over the winter. Is there any advantages to digging in the fall rather than the spring?
Timberjack I have no advice since your conditions are completely different from what we have down South but I'm interested in the procedure and why it would be done this way.
How deep does the frost get there? "Here", 4 feet is common, but 8+ feet is not unheard of. (Couple winters ago, water lines were freezing 12 feet under.) Having said that, when I built in 2004, they dug the basement with no issue mid-April. If we can do that in Manitoba, you shouldn't have any issues in Ontario! And, "here" you wouldn't get a contractor right now anyways.... they are too busy trying to finish what they have lined up before the snow flies and ground freezes! Andrew
The only reason I can think of would be that any slight over ex would have settled, but, if left open over the winter sloughing will occur and the grade would have to be finished in the spring anyway. Depending on the size of your basement excavation and the reach of the equipment, leaving open until spring might require ramping in order to gain access for finishing. Plus, erosion will occur on the material that is stockpiled for backfill. Were it me I would not do it.
I wouldn't you would get a lot of cave in's and setiment in the bottom of the hole that you could not pour on then without putting a machine in the hole you got a lot of shovel work to. Beat me to it I was too slow on the key board
Thanks everyone for the sound advice. I can see now that there could be issues/problems with digging in the fall. I'll heed the good advice and hold off until spring. Muchas gracias.
Around here we "tarp" an excavation that might want to go ahead during the winter. Put down 6-12" of hay etc. and a tarp over the top, then weight down the tarp. You can usually come back at any point, scrape the tarp off and dig away. The mason's will hate you but you can do it.
Good idea for an early spring start.
You mean dig the hole and leave it sit open all winter without a foundation? I wouldn't, too much material will sluogh back into the hole and you'll have to re-dig it come spring time (like everyone else said) There was a basement last winter that got dug mid December, they dug it and there was quite a bit of frost in the ground, well they poured the foundation and we got some rain and a bunch of the sidewalls that were frozen sloughed in against the new concrete. Someone ended up having to re-pour some walls. :Banghead
If you are removing muskeg to build on grade it is actually good to let it set over winter the freeze thaw cycle will take care of settling issues.
We consider 4' to be frost depth around here but we dig year round and cover the excavation with blankets made for insulating concrete while it cures to protect it from freezing.Usually the contractor doing the concrete work is so happy to have any work when it is so cold they will be there with the insulation while you are digging to make sure that it doesn't freeze and the town building inspectors have to approve it anyway before they can pour.I have dug a lot of cellars in the middle of the winter,especially in housing developments where they don't want to wait for anything and have to keep their crews busy.Ron G
I dug basements in Winnipeg and that area for several years it was almost better to dig during the winter as the ground was always so soft, usually the basements were on pilings so it didn't matter if you got frost in the floor and was often beneficial for the piling rig if they couldn't be there that specific day. Most piling rigs were mounted on a truck so if they had to go in silt they'd be stuck right away. Also there was no threat of rain to turn a freshly excavated basement in to a pool, not to mention with the ground being frozen it can make life easier for the concrete guys and later on the framers as they can get around the job site without being up their ankles in mud all the time. If the basements was to be on a conventional footing the floor was tarped with an insulated tarp and often heated with a propane forced air heater (Herman Nelson type). The only problem was backfilling the basement as the earth was frozen like concrete and had to be broken up with an excavator and even then still settled a lot in the spring. I attached some pictures of a mostly built basement with some hoarding over the garage area so they could pour the garage floor this was more of a luxury home, the regular 'cookie cutter' type wouldn't get a garage floor till spring time.
Not all of them uploaded here's the rest.
I see no advantage to leaving it open all winter in soil that has enough bearing to hold the building. Insulated blankets would not prevent frost from penetrating long term here, its only a short term solution when you are actively working on the job.
The blankets are only intended to protect it overnight and then they use them to insulate the fresh concrete footings.The temps here have to be 28 degrees and rising to get the approval to pour.Ron G
The insulated blankets here are only one component to keeping the concrete from freezing they were also using propane forced air heaters otherwise tarps or not it would freeze especially with our -40C winter weather.
Not sure what part of Ontario you are in, but I think your spring comes sooner in southern Ontario, than here in New Brunswick. If you have a lot of snow cover on your lot, frost shouldn't be too hard to dig in the spring. I've seen basements dug here in early spring with no problems. To me, if you dig the hole, and leave it sit all winter, you would be pouring your footings on ground that has not thawed in spring, where as a fresh spring dig would be well below the frost line when you pour.